VAL - QB64 Wiki

VAL

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The VAL Function returns the decimal numerical equivalent value of a STRING numerical value.


Contents

Syntax

value = VAL(string_value$)


  • VAL converts string numbers to numerical values including decimal point values and prefixed "&H" hexadecimal, "&O" octal.
  • VAL conversion stops at non-numeric characters except for letter "D" or "E" exponential notation values.
String values with "D" and "E" letters between numbers may be converted also! EX: VAL("9D4") = 90000
  • If the first string character is not a number VAL returns 0. VAL may return erratic values with "%" or "&" starting characters.
  • Hexadecimal HEX$ string values with the "&H" prefix can be converted to a decimal value with digits 0 to 9 and letters A to F, like; dec = VAL("&H"+hexvar$).
  • Octal OCT$ string values with the "&O" prefix can be converted to a decimal value with digits from 0 to 7 only.
  • Presently VAL cannot convert QB64 binary &B prefixed strings from binary to decimal in QB64.
  • For character values of ASCII data use ASC to get the value.
  • In QB64 use an INTEGER return variable to hold integer values returned by VAL Hex strings: value% = VAL("&HFFFF") = -1


Example 1: Differences in values returned with Qbasic and QB64:

PRINT VAL("&H") '203 in QB, 0 in QB64 PRINT VAL("&HFFFF") ' -1 QB, 65535 in QB64 PRINT VAL("&HFFFF&") '65535 in both

Explanation: A quirk in Qbasic returned VAL values of 203 for "&" and "&H" that was never fixed until PDS(7.1).


Example 2: Converting a string with some number characters

text$ = "1.23Hello" number! = VAL(text$) PRINT number!

1.23


Example 3: Converting literal and variable string values to numerical values.

a$ = "33" PRINT VAL("10") + VAL(a$) + 1

44

Explanation: 10 + 33 + 1 = 44, the strings were converted to values.
You have to convert the string to values in order to use them in a mathematical expression also since mixing strings with numbers isn't allowed. VAL will stop at a text letter so VAL("123G56) would return 123.
If VAL wasn't used the program would break with an error, as you can't add the value 1 to a string, if the 1 was a string ("1") then the program would return "10331", but now since we used VAL, the numbers were added as they should.


Example 4: Converting a hexadecimal value to decimal value using HEX$ with VAL.

decnumber% = 96 hexnumber$ = "&H" + HEX$(decnumber%) 'convert decimal value to hex and add hex prefix PRINT hexnumber$ decimal% = VAL(hexnumber$) PRINT decimal%

&H60 96

Explanation: HEX$ converts a decimal number to hexadecimal, but VAL will only recognize it as a valid value with the "&H" prefix. Especially since hexadecimal numbers can use "A" through "F" in them. Create a converter function from this code!


See also:



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